The present invention relates to apparatus for handling sheets of print receiving material during a print operation and, more particularly, to a paper handling system for an ink jet printer in which sheets of print receiving medium are successively loaded onto a sheet supporting drum which is rotated adjacent a print head. Each sheet is removed from the drum after printing on the sheet has been accomplished during a plurality of drum rotations.
Such a printer, utilized in an ink jet copier is disclosed in U.S. Pat. No. 4,106,061, issued Aug. 8, 1978, to Burnett. The Burnett patent discloses a paper supporting drum upon which is mounted a sheet of copy paper. The drum has associated therewith an ink jet printer which is moved parallel to the axis of rotation of the drum during a plurality of drum rotations as scanning is performed in a corresponding manner across an original document. A plurality of vacuum belts cooperate with evacuated chambers beneath the belts to transfer copy paper from a supply tray to the drum for printing and, after the printing operation is completed, to transfer the printed copies to a storage tray. Printing is accomplished during a plurality of rotations of the paper supporting drum during which time the ink jet printer prints in a helically interlaced pattern on the copy paper.
Other arrangements are known for depositing drops along a plurality of print lines on a sheet of paper mounted on a rotating drum, such as shown in U.S. Pat. No. 3,689,693, issued Sept. 5, 1972, to Cahill et al. Cahill discloses a plurality of jet streams directed toward the print receiving medium such that each jet stream will print a band of adjacent print lines which do not interlace with print lines printed by others of the jet streams.
In prior art printers, loading a sheet of paper onto a rotating drum for printing and subsequently removing the sheet of paper from the drum after printing have generally taken a substantial amount of time for each printed sheet. Such printing devices have generally processed only a single sheet of paper at a time, i.e., a sheet is printed and completely removed from the drum and transported to the appropriate storage tray prior to initiation of the loading operation for the next sheet to be printed.
U.S. Pat. No. 4,029,009, issued June 14, 1977, to Kuhn et al discloses a sheet handling arrangement in which a sheet is loaded onto a drum prior to complete removal of the sheet previously loaded onto the drum. The drum, however, is a transfer roller, located between print rollers, which is designed specifically for reversing the sheet side for side during the transfer between the printing rollers. The transfer roller is not appropriate for use as a paper supporting drum in a system requiring a plurality of passes of a sheet past a printing device.